FA-7071 / Proxy forwarding / Open access

Buffer watermark resume requires low threshold · case 01

Buffer watermark resume requires low threshold.

Verified by executionVariant 1 · 4 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

The faulty implementation uses `paused and size < low` for the buffer-watermark-resume-requires-low-threshold decision.

VERIFIED REPAIR

Apply the explicit buffer-watermark-resume-requires-low-threshold contract, including the tested boundary and negative cases.

Unsuccessful approach: The attempted repair uses `size <= low` and still violates a separate fixture.

Case contract

Bounded offline decision model: buffer watermark resume requires low threshold. Inputs are already validated protocol fields; the explicit fixtures define the supported policy, not a complete protocol implementation.

Why this case matters

This deterministic proxy forwarding model isolates the buffer-watermark-resume-requires-low-threshold policy at a network component boundary.

1 / The failure

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(paused, size, low):
    return paused and size < low
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 2, 2), True)", "check('fixture 2', solve(False, 1, 2), False)", "check('fixture 3', solve(True, 3, 2), False)", "check('fixture 4', solve(True, 0, 2), True)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`False`	`False`	Passed
fixture 3	`False`	`False`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`False`	`True`	Failed

SHA-256 / 39678c12d1ef444f9767bfea7c096ab8d3782cb2bec4e0e5602a5c64ff62396d

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(paused, size, low):
    return size <= low
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 2, 2), True)", "check('fixture 2', solve(False, 1, 2), False)", "check('fixture 3', solve(True, 3, 2), False)", "check('fixture 4', solve(True, 0, 2), True)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`True`	`False`	Failed
fixture 3	`False`	`False`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`True`	`True`	Passed

SHA-256 / 79e53c2cefd2dd5a3beaa68f31af668e5a18dcf69085f2cd467473aec7440e5c

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import ipaddress
import re
from urllib.parse import urlsplit, urljoin
N = 1
observations = []
def solve(paused, size, low):
    return paused and size <= low
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
_fixtures = ["check('fixture 1', solve(True, 2, 2), True)", "check('fixture 2', solve(False, 1, 2), False)", "check('fixture 3', solve(True, 3, 2), False)", "check('fixture 4', solve(True, 0, 2), True)"]
for _line in _fixtures[N % len(_fixtures):] + _fixtures[:N % len(_fixtures)]:
    exec(_line)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)

Boundary fixture	Actual	Expected	Outcome
fixture 2	`False`	`False`	Passed
fixture 3	`False`	`False`	Passed
fixture 4	`True`	`True`	Passed
fixture 1	`True`	`True`	Passed

SHA-256 / fbff4f705897f0f09372e089ee23d2772bccd76f02cb9d9b3e4d534a3ec59cf9

Verification & scope

Bounded deterministic policy model over validated inputs; not a complete protocol stack or an interoperability claim. The five variants rotate the same explicit fixture set. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:38:08.025987+00:00.

Case digest / a116729c17bd1ddaad9a1d96813872ce1d33bd1d022d1e6910f6c3ad9f96f924